Featured Research

Fossil Evidence Of Missing Link In The Origin Of Seals, Sea Lions, Walruses Found In Canadian Arctic

Date:

April 23, 2009

Source:

Carnegie Museum of Natural History

Summary:

Researchers from the United States and Canada have found a fossil skeleton of a newly discovered carnivorous animal, Puijila darwini. New research suggests Puijila is a "missing link" in the evolution of the group that today includes seals, sea lions, and the walrus.

Researchers from the United States and Canada have found a fossil skeleton of a newly discovered carnivorous animal, Puijila darwini. New research suggests Puijila is a "missing link" in the evolution of the group that today includes seals, sea lions, and the walrus.

Related Articles

The analysis of the skeleton and support for the hypotheses that pinniped origins can be found in the Arctic will be described in the April 23 issue of the journal Nature.

Modern seals, sea lions, and walruses all have flippers—limb adaptations for swimming in water. These adaptations evolved over time, as some terrestrial animals moved to a semi-aquatic lifestyle. Until now, the morphological evidence for this transition from land to water was weak.

"The remarkably preserved skeleton of Puijila had heavy limbs, indicative of well developed muscles, and flattened phalanges which suggests that the feet were webbed, but not flippers. This animal was likely adept at both swimming and walking on land. For swimming it paddled with both front and hind limbs. Puijila is the evolutionary evidence we have been lacking for so long," says Mary Dawson, curator emeritus of Carnegie Museum of Natural History.

Portions of the Puijila darwini specimen were found in 2007 in deposits that accumulated in what was a crater lake in coastal Devon Island, Nunavut, Canada. A subsequent visit in 2008 yielded the basicranium, an important structure for determining taxonomic relationships.

Paleobotanic fossils indicate this location during the Miocene had a cool, coastal temperate environment, similar to present-day New Jersey. Given that freshwater lakes would freeze in the winter, it is likely that Puijila would travel over land to the sea for food. The transition from freshwater to saltwater in semi-aquatic mammals has been hypothesized for some time, first by Charles Darwin, who wrote in On the Origin of Species by the Means of Natural Selection, "A strictly terrestrial animal, by occasionally hunting for food in shallow water, then in streams or lakes, might at last be converted in an animal so thoroughly aquatic as to brace the open ocean."

"The find suggests that pinnipeds went through a freshwater phase in their evolution. It also provides us with a glimpse of what pinnipeds looked like before they had flippers," says Natalia Rybczynski, leader of the field expedition.

The animal is described as having a long tail, and fore-limbs comparatively proportionate to modern carnivorous land animals as opposed to pinnipeds. It is the first mammalian carnivore found at the site. Other fossils found include two taxa of freshwater fishes, one bird, and four mammalian taxa: shrew, rabbit, rhinoceros, and small artiodactyl (small short-legged herbivores, ancestors to modern giraffes and deer).

The earliest well-represented pinniped, Enaliarctos—a marine form with flippers—has been found on northern Pacific shores of North America. It had been theorized for some time that pinniped evolution had been centered around the Arctic; the discovery of Puijila adds credence to this theory.

Co-authors of the paper are Natalia Rybczynski, research scientist at Canadian Museum of Nature, Ottawa, Ontario; Mary R. Dawson, curator emeritus of vertebrate paleontology at Carnegie Museum of Natural History in Pittsburgh, Pennsylvania; and, Richard H. Tedford, curator emeritus of paleontology at American Museum of Natural History, New York, New York. Skeletal and fully-fleshed out illustrations of this animal were done by Mark Klingler, scientific illustrator at Carnegie Museum of Natural History.

Carnegie Museum of Natural History. "Fossil Evidence Of Missing Link In The Origin Of Seals, Sea Lions, Walruses Found In Canadian Arctic." ScienceDaily. ScienceDaily, 23 April 2009. <www.sciencedaily.com/releases/2009/04/090422132832.htm>.

Carnegie Museum of Natural History. (2009, April 23). Fossil Evidence Of Missing Link In The Origin Of Seals, Sea Lions, Walruses Found In Canadian Arctic. ScienceDaily. Retrieved March 31, 2015 from www.sciencedaily.com/releases/2009/04/090422132832.htm

Carnegie Museum of Natural History. "Fossil Evidence Of Missing Link In The Origin Of Seals, Sea Lions, Walruses Found In Canadian Arctic." ScienceDaily. www.sciencedaily.com/releases/2009/04/090422132832.htm (accessed March 31, 2015).

More From ScienceDaily

More Plants & Animals News

Featured Research

Mar. 31, 2015  Until now electric fences and trenches have proved to be the most effective way of protecting farms and villages from night time raids by hungry elephants. But researchers think they may have come up ... full story

Mar. 31, 2015  Researchers have detected a human fingerprint deep in the Borneo rainforest in Southeast Asia. Cold winds blowing from the north carry industrial pollutants from East Asia to the equator, with ... full story

Mar. 31, 2015  A team of engineers and biologists reports new progress in using computer modeling and 3D shape analysis to understand how the unique grasping tails of seahorses evolved. These prehensile tails ... full story

Mar. 31, 2015  As the five-year anniversary of the explosion of the Deepwater Horizon oil rig approaches, a new report looks at how twenty species of wildlife are faring in the aftermath of the ... full story

Mar. 31, 2015  Scientists have uncovered the earliest fossilized evidence of an insect caring for its young. The findings push back the earliest direct evidence of insect brood care by more than 50 million years, ... full story

Mar. 31, 2015  New research has scientists re-thinking how a lethal fungus grows and kills immune cells. The study hints at a new approach to therapy for Candida albicans, one of the most common causes of ... full story

Mar. 31, 2015  The most virulent strains of Streptococcus suis, the leading cause of bacterial meningitis in adult humans in parts of southeast Asia and in pigs around the world, are likely to have evolved and ... full story

Mar. 31, 2015  Darwin's evolutionary theory predicts survival of the fittest. So why do different survival tactics co-exist, if evolution should always favor the winning strategy? To answer that question scientists ... full story

Mar. 31, 2015  Scientists have discovered why the first buds of spring come increasingly earlier as the climate changes. As the climate changes the sweet spot for seeds comes earlier in the year, so first flowers ... full story

Mar. 31, 2015  Paleontologists have discovered two new species of Saurichthys. The ~242 million year old predatory fishes were found in the fossil Lagerstδtte Monte San Giorgio, in Ticino. They are distinct from ... full story

Featured Videos

Bionic Ants Could Be Tomorrow's Factory Workers

Reuters - Innovations Video Online (Mar. 30, 2015)  Industrious 3D printed bionic ants working together could toil in the factories of the future, says German technology company Festo. The robotic insects cooperate and coordinate their actions and movements to achieve a common aim. Amy Pollock reports.
Video provided by Reuters

Lions Make Surprise Comeback in Gabon

AFP (Mar. 30, 2015)  Lions have made a comeback in southeast Gabon, after disappearing for years, according to live footage from US wildlife organisation Panthera. Duration: 00:32
Video provided by AFP

Ancient Egyptian Beer Making Vessels Discovered in Israel

AFP (Mar. 30, 2015)  Fragments of pottery used by Egyptians to make beer and dating back 5,000 years have been discovered on a building site in Tel Aviv, the Israeli Antiquities Authority said on Sunday. Duration: 00:51
Video provided by AFP

Related Stories

Feb. 11, 2015  The oldest known fur seal has been discovered by a Geology PhD student at New Zealand's University of Otago, providing a missing link that helps to resolve a more than 5-million-year gap in fur ... full story

Feb. 19, 2014  Modern pinnipeds (the group that includes seals, sea lions and walruses) show a range of sexual dimorphism (large differences in size between males and females) and mating systems that span the ... full story

Aug. 24, 2011  U.S. Geological Survey Alaska Science Center researchers, in cooperation with the Native Village of Point Lay, will attempt to attach 35 satellite radio-tags to walruses on the northwestern Alaska ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.